(a) Technical Field
The inventive concept relates to a display device including a touch sensor. More particularly, the inventive concept relates to a display device including a hybrid touch sensor for sensing a touch position and a touch pressure.
(b) Description of the Related Art
Display devices such as a liquid crystal display and an organic light emitting display, portable transmission devices, and other information processing devices perform a function by using various input devices. Recently, as the input device, input devices including a touch sensing device have been frequently used.
A touch sensing function is used to find contact information such as whether an object approaches or touches a screen and a touch location thereof by sensing changes in pressure, charges, light, and the like which are applied to the screen of the display device, when the user writes text or draws figures by approaching or touching the screen using a finger or a touch pen. The display device receives an image signal based on the contact information to display an image.
Such a touch sensing function may be implemented through a touch sensor. The touch sensor may be classified into various types such as a resistive type, a capacitive type, an electromagnetic resonance (EMR) type, and an optical type.
For example, in the case of the resistive type touch sensor, two electrodes that face each other and are separated from each other may contact each other by pressure caused by an external object. When the two electrodes contact each other, a contact position is known by recognizing changes of voltage induced by changes of resistance at the position.
For example, the capacitive type of touch sensor includes a sensing capacitor formed by a plurality of sensing electrodes which may transfer sensing signals, and senses a change in capacitance of the sensing capacitor generated when a conductor such as a finger approaches the touch sensor to determine existence of a touch, a touch position, and the like. Regarding the capacitance type of touch sensor, a touch is sensed when a user contacts a touch screen, and a contact by a conductive object is needed.
The touch sensor may be built in the display device (i.e., in-cell type) or be formed outside of the display device (i.e., on-cell type). An additional touch sensor panel may be attached to the display device (i.e., add-on cell type).
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.